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Humming Noise in Car When Parked

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Ever been in your garage several hours after parking your car and, all of a sudden, you hear a funny humming sound from underneath the vehicle? There are several reasons your car may produce this sound when parked.

As such, it shouldn’t be something to worry you or involve your mechanic unless the problem persists. The humming or buzzing sound you hear can result from different systems in your vehicle, such as the drive belt or exhaust systems.

In this humming noise guide, we’ll take you through the causes and how to fix this noise that comes hours after parking your car.

What Causes Humming Noise in Car When Parked?  

Humming noise after parking your vehicle can only relate to parts of the car that move even when the vehicle isn’t moving. This could be areas like the drive belt or the evaporative emission pump that happens naturally in vehicles.

Several components can produce a humming or buzzing noise in the drive belt, such as a power steering pump, water pump, and air conditioning compressor. When air finds an escape route, it could easily cause humming noise.

In addition, the noise could be a result of the car’s evaporative emission check that happens approximately five hours after turning off the engine. It doesn’t indicate a malfunctioning engine check light since it’s a normal mechanism for the car.

Now you’re probably asking, what’s more about the evaporative emission check? Let’s see that below;

 Emission Leak Check and Enabling Conditions?

The evaporative emission leak check produces a humming sound involving pumping pressure to the gas tank to ensure its tightly sealed. The pressure system tests the tank’s filler neck, evaporative canister, and gas cap.

Given that the fuel storage system holds the pressure, the vehicle’s computer system concludes that there is no leakage and that everything is intact. Therefore, you won’t notice a check engine light despite the humming noise.

On the other hand, if the system can’t hold the pressure inside, the humming noise often occurs since the pressurizing pump has to come on every few hours. As a result, the vehicle’s computer system assumes there’s a leakage, thus turning on the check engine light.

Your take home, if the engine check light turns on in the process, first check whether the gas tank cap is airtight. This alone is a significant cause of fuel system pressure leak. However, if that isn’t the solution and the check engine light persists, that’s a direct ticket to your mechanic.

 Enabling Conditions of Evaporative Emission Leak Check? 

This process naturally happens 5 hours after your turn off your vehicle engine. Nevertheless, if the engine coolant temperature retains a temperature of 350 C (950 F) and above, the process extends from 5 to 7 hours since it depends on temperature variations.

Besides, even after the 7 hours, if the temperature remains above 350 C, the system automatically extends the time to 9.5 hours.

Other enabling conditions that trigger evaporative emission leak check include;

·         An altitude of 2400 m (8000 feet) and below

·         The vehicle’s battery voltage should be 10.5 v and above

·         The vehicle’s ignition switch should be off.

·         The engine coolant and intake air temperatures should be between 4.4 to 350 C or 400 to 950 F.  

The enabling conditions are part of the evaporative emission control system. The system detects faults within the gas tank and implements a functional and onboard refueling vapor recovery.

Another use of the evaporative emission control system is to prevent the return flow of fuel from the engine to the gas tank. It incorporates various gas tank parts such as fuel filter, sender gauge with fuel suction pump, and pressure regulatory assembly.

How To Fix Humming Noise in Car When Parked? 

To fix the humming noise problem, you first have to assess where the noise is coming from. Since the noise comes when the car is idle, you can place your vehicle in an elevated place and lie beneath as you listen to where the noise is coming from.

From that position, it’s easy to identify which side where the humming noise is coming from. If the check engine light turns on due to the noise, tighten the gas tank cap and keep observing.

Now, when underneath your car, if the noise is coming from the position just under the driver’s seat, be sure to note that it’s the effect of the fuel pump when initiating the pressure test.

However, if the humming sound comes from the rear side of your vehicle, it might be a faulty emission canister. Changing the emission canister should work if the humming or buzzing sound persists. For that, you can visit your mechanic for assistance.

How Can You Tell If The Check Detects A Faulty 

One way is when the check engine turns on. When the evaporative emission check runs and the gas tank fails to withhold the required pressure, the check engine turns on.

Nevertheless, the check engine turns on if the gas tank cap is not air-tight. As such, find out if the tank cap is closed before making further assumptions.

Of importance, note that this is not the only reason a check engine turns on. There are many other issues, only that this is one of the common ones.

Also, when the EEC keeps running every few minutes and the check engine isn’t on, there might be a slight leak around the gas tank compartments.

Although it’s not a cause of alarm, have it checked when you drive to your mechanics.   

On Humming Noise in Car When Parked

In conclusion, if you’ve frequently experienced the humming noise several hours after turning off your vehicle noise, don’t fume thinking it’s yet another visit to the mechanic. It might be a quick fix issue that takes you a few minutes.

Therefore, assess the vehicle keenly and establish where the noise is coming from. From there, the next step is identifying whether it’s the normal evaporative emission check or another issue within your car.

Take the necessary precautions like tightening the gas tank cap, and if the noise persists, visit your mechanic for diagnosis. 

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